In the related art, an image pickup apparatus that can discretely distribute focus detection pixels between pixel groups of a photoelectric conversion unit and calculate an object distance based on signals from the focus detection pixels is disclosed in Japanese Patent Application Laid-Open No. 2000-156823 (hereinafter, referred to as “Patent Document 1”). If the configuration that is disclosed in Patent Document 1 is used, a distance distribution on an object included in a photographed image can be obtained.
As a method that restores a blurred image and generates a blur restored image, for example, a method using a Wiener filter, a general inverse filter or a projection filter is used. A technique for correcting the blur using the above method is disclosed in Japanese Patent Application Laid-Open No. 2000-20691 (hereinafter, referred to as “Patent Document 2”). By using the technique that is disclosed in Patent Document 2, a deterioration function can be calculated by a physical analysis based on a photographing condition or estimation based on an output form a measuring device in the image pickup apparatus and a blurred image can be restored using an image restoration algorithm called deconvolution.
In general, an object distance to be focused may be determined by a focus state at the time of photographing. For this reason, the object distance to be focused cannot be changed after photographing. However, if an object distance distribution in a photographed image is obtained using the technique disclosed in Patent Document 1 and blur correction is performed using the blur correction technique disclosed in Patent Document 2, the object distance to be focused can be changed after photographing.